I like it.
W/r/t beveled edge between 5 and 7: I agree, flow reversal is aided by an large radius in the "V", a sharp edge reduces cross-flow.

Harley-Davidson learned this in the opposite direction. In the the 1940s with a "Y" shaped manifold feeding both 45 degree cylinders (315-405 degree split), the V split was sharp. Material was added on outside and removed from inside to re-shape into a radius, this allows charge already in the non-intake manifold leg and port (up to the valve) to reverse, follow the vacuum source and flow back to the cylinder on intake.